This invention relates to fault-tolerant computer networks in which multiple users can write data to a shared random access data storage device. Typically, multiple shared data sets in the form of shared files are stored on one or more storage devices or logical drives attached to a network server computer providing random access to the shared data sets. In a common configuration, a high-performance network file server computer supports either a wired or wireless network of intelligent workstations by means of which users can communicate, one with another and share network services, for examples high capacity storage devices, drives or drive systems, where shared network data is stored for use by workstation users.
More particularly, the invention relates to computer systems having what has been described as level three fault tolerance. Level three fault tolerance is usually definable as including means enabling users to continue to access and process shared data after the failure of an intelligent host, or file server, supporting access to a storage device holding the shared data. For effective commercial operation, for example, to keep bank tellers in business, and for most practical purposes, the shared data must continue to be available in a substantially automatic manner, after a server failure, without any need to reconnect or to restore any hardware, and with no or minimal user or supervisor intervention being required to permit processing to continue.